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The cosmic microwave background is a uniform 2.7 Kelvin radiation that permeates the entire universe. Although it was postulated almost 50 years before, Penzias and Wilson discovered the cosmic microwave background accidentally in the 1970s. Working at Bell Labs, these two scientists were using a radio telescope to observe distant stars. They found, however, that no matter where they pointed their telescope they observed an approximately 3 Kelvin background signal. After convincing themselves that this signal was real and not some artifact of their instrument, they consulted with a team at Princeton University that had been searching for the cosmic microwave background. The Princeton team confirmed what Penzias and Wilson had found. Apparently, Penzias and Wilson had accidentally stumbled upon the oldest observable relic of the early universe.

Why does the cosmic microwave background exist and permeate all of space? Just an instant after the Big Bang, all matter in the universe was so energetic, or hot, that it existed as free particles known as “quarks.” In the fractions of a second following, the universe expanded and cooled until the quarks lost enough energy to form electrons, protons, and neutrons, the building blocks of ordinary matter. Photons, the smallest particles of light, also filled the universe and were so energetic that they “bounced” off electrons, keeping the electrons and protons from forming atoms. After approximately 400,000 more years, the photons lost enough energy that atoms could form readily. Without any lone electrons off of which photons could “bounce,” the photons began streaming unimpeded all through the universe, mostly unchanged but for one exception. Due to the further expansion and cooling of the universe, these photons have cooled to just 2.7 degrees above absolute zero. It was these same photons that Penzias and Wilson observed approximately 13.6 billion years later here on Earth.

1. Which of the following most accurately expresses the author’s intent in writing the passage?

(A) To describe the discovery and reason for the cosmic microwave background(B) To explain how science discoveries can be made accidentally(C) To argue that the cosmic microwave background is the oldest observable relic of the universe(D) To defend the work of Penzias and Wilson(E) To support the theory of the Big Bang using the cosmic microwave background

3. According to the passage, with which of the following would the author most likely agree regarding the discovery of Penzias and Wilson?

(A) It was not as important as the signal for which they were originally searching.(B) The telescope belonging to Penzias and Wilson was more sensitive than that of the Princeton team.(C) Penzias and Wilson would not have discovered the cosmic microwave background if it had been more than 3 Kelvin in temperature.(D) Penzias and Wilson did not initially understand the implications of their results.(E) Penzias and Wilson did not believe that their signal was real when they took their discovery to the Princeton team.

Re: The cosmic microwave background is a uniform 2.7 Kelvin radiation that
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03 Dec 2019, 20:21

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1. Which of the following most accurately expresses the author’s intent in writing the passage?

para-1--explains how the cosmic microwave background was discoveredpara-2--explains the reason for the existence of cosmic microwave background

(A) To describe the discovery and reason for the cosmic microwave background---(correct)

2. According to the passage, which of the following events occurred first after the Big Bang?

please see the second line in 2nd para--

Just an instant after the Big Bang, all matter in the universe was so energetic, or hot, that it existed as free particles known as “quarks.--just after big bang matter existed as quarks

(C) All matter existed as particles known as “quarks.” --is the correct answer

3. According to the passage, with which of the following would the author most likely agree regarding the discovery of Penzias and Wilson?

(A) It was not as important as the signal for which they were originally searching.--not mentioned in the passage (incorrect)

(B) The telescope belonging to Penzias and Wilson was more sensitive than that of the Princeton team.--no comparison regarding the telescope of Penzias and Wilson and the Princeton team is mentioned in the passage (out of scope)

(C) Penzias and Wilson would not have discovered the cosmic microwave background if it had been more than 3 Kelvin in temperature.--there is nothing mentioned what would have happened if the cosmic microwave background had been more than 3 Kelvin in temperature.(incorrect)

(D) Penzias and Wilson did not initially understand the implications of their results. (correct)

(E) Penzias and Wilson did not believe that their signal was real when they took their discovery to the Princeton team.--it is mentioned in the passage that after convincing themselves that their signal was real they consulted the Princeton team--this answer choice is the opposite of what is mentioned in the passage (incorrect)